1. Field of the Invention
This invention relates to the cleaning of a body of liquid. In particular, it relates to a method of cleaning the body of liquid and to an apparatus for cleaning such a body of liquid. The body of liquid may, in particular, be a swimming pool.
2. Description of Prior Art
A large number of automatic pool cleaning systems have been devised and are in use. Some of such systems work under pressure, utilising pressurised water supplied by a pump and filter system of the pool or by a special pump.
One pool cleaning system is described in U.S. Pat. No. 3,261,371 issued to Vernon which has a number of flexible hoses each with a nozzle at its end, through which the pressurised water exits. A reaction thrust is exerted on each nozzle so that the flexible tubes move sinuously over the pool floor, with the ends of the tubes waving gently back and forth over arcs that vary. Any sediment in the pool is thus repeatedly loosened and held in suspension until it is removed by a filtration system of the swimming pool system. The system described in this patent has a main tube with a number of branch tubes that branch from the main tube. At the branch points, there are a pair of jets, there being one jet on one side of the main tube and the other on the other side thereof with both jets pointing in a downstream direction at an angle to the longitudinal axis of the main tube. Although this system will dislodge small particles of dirt, larger objects such as leaves, pieces of paper and other debris will quickly sink back to the floor of the swimming pool and will not remain in suspension and accordingly will not be removed by the filtration system.
U.S. Pat. No. 4,040,864 to Steeves discloses the use of a bag that is secured to the free end of a flexible tube that also has a nozzle to cause displacement of the tube. The Steeves system further has a floating body that has a rotatable wheel which engages the sides of the pool to propel the body around the pool, thereby dragging the tube and bag around in the pool. As the floating body is forced to follow the walls of the pool the bag will not follow a totally random path and, with most pools, the bag will not clean everywhere and dirt and debris will settle out, most particularly in corners.
A device for cleaning the side walls of a swimming pool at the water line region thereof is disclosed in U.S. Pat. No. 4,429,429 to Altschul. This device is buoyant and is attached to the end of a flexible tube. It has propulsion jets which point towards the hose, so that the device pulls the hose along. The device further has a bag which has a mouth pointing away from the hose with an auxiliary jet that is located at the mouth of the bag and is directed into the bag, towards the hose. The device is designed and intended to move along the side walls at the water line region, and it cannot remove dirt from the body of the water, or from the floor of the swimming pool, or from the side walls of the swimming pool below the water line.
A further system is disclosed in U.S. Pat. No. 4,281,995 to Pansini. This system has a first length of hose, the inlet of which is connected to a supply of water under pressure, and its outlet is connected to a float. A further length of hose has its inlet end carried by the float and in fluid communication with the outlet of the first hose, with the free end of the further hose also being supported by a float. Both the first and further hoses have jets which are directed upstream, so that the jets tend to maintain the hoses under tension.